Field
The present invention relates to circuitry that can be used to perform or support sum-of-products operations.
Description of Related Art
In neuromorphic computing systems, machine learning systems and circuitry used for some types of computation based on linear algebra, the sum-of-products function can be an important component. The function can be expressed as follows:
      f    ⁡          (              x        i            )        =            ∑              i        =        1            M        ⁢                  ⁢                  W        i            ⁢              x        i            
In this expression, each product term is a product of a variable input Xi and a weight Wi. The weight Wi can vary among the terms, corresponding for example to coefficients of the variable inputs Xi.
The sum-of-products function can be realized as a circuit operation using cross-point array architectures in which the electrical characteristics of cells of the array effectuate the function.
For high-speed implementations, it is desirable to have a very large array so that many operations can be executed in parallel, or very large sum-of-products series can be performed. In the systems, there can be a very large number of inputs and outputs, so that the total current consumption can be very large.
It is desirable to provide structures for sum-of-products functions suitable for implementation in large arrays, and that can be more energy-efficient.